Many abnormal medical conditions in humans and other mammals have been associated with disease and other aberrations along the lining or walls that define several different body spaces. In order to treat such abnormal conditions of the body spaces, medical device technologies adapted for delivering various therapies to the body spaces using the least invasive means possible.
As used herein, the term “body space,” including derivatives thereof, is intended to mean any cavity within the body which is defined at least in part by a tissue wall. For example, the cardiac chambers, the uterus, the regions of the gastrointestinal tract, and the arterial or venous vessels are all considered illustrative examples of body spaces within the intended meaning.
The term “vessel,” including derivatives thereof, is herein intended to mean any body space which is circumscribed along a length by a tubular tissue wall and which terminates at each of two ends in at least one opening that communicates externally of the body space. For example, the large and small intestines, the vas deferens, the trachea, and the fallopian tubes are all illustrative examples of vessels within the intended meaning. Blood vessels are also herein considered vessels, including regions of the vascular tree between their branch points. More particularly, the pulmonary veins are vessels within the intended meaning, including the region of the pulmonary veins between the branched portions of their ostia along a left ventricle wall, although the wall tissue defining the ostia typically presents uniquely tapered lumenal shapes.
One means of treating body spaces in a minimally invasive manner is through the use of catheters to reach internal organs and vessels within a body space. Electrode or electrophysiology (EP) catheters have been in common use in medical practice for many years. They are used to stimulate and map electrical activity in the heart and to ablate sites of aberrant electrical activity. In use, the electrode catheter is inserted into a major vein or artery, e.g., the femoral artery, and then guided into the chamber of the heart that is of concern in order to perform an ablation procedure.
Steerable catheters are generally well-known. For example, U.S. Pat. No. RE 34,502 describes a catheter having a control handle comprising a housing having a piston chamber at its distal end. A piston is mounted in the piston chamber and is afforded lengthwise movement. The proximal end of the catheter body is attached to the piston. A puller wire is attached to the housing and extends through the piston and through the catheter body. The distal end of the puller wire is anchored in the tip section of the catheter to the side wall of the catheter shaft. In this arrangement, lengthwise movement of the piston relative to the housing results in deflection of the catheter tip section. The design described in U.S. Pat. No. RE 34,502 is generally limited to a catheter having a single puller wire.
Bidirectional steerable catheters are also generally well known, as a variety of designs have been proposed. In many such designs, such as those described in U.S. Pat. Nos. 6,066,125, 6,123,699, 6,171,277, 6,183,463 and 6,198,974, a pair of puller wires extend through a lumen in the main portion of the catheter shaft and then into opposing off axis lumens in a deflectable tip section where the distal end of each puller wire is attached to the outer wall of the deflectable tip. Pulling one wire in a proximal direction causes the tip to deflect in the direction of the off axis lumen in which that wire is disposed.
In other designs, such as those described in U.S. Pat. No. 5,531,686, the puller wires are attached to opposite sides of a rectangular plate that is fixedly mounted at its proximal end and extends distally within a lumen in the tip section. In this arrangement, pulling one of the wires proximally causes the rectangular plate to bend in the direction of the side to which the pulled puller wire is attached, thereby causing the entire tip section to deflect.
In all of the designs for a steerable catheter, the method of manufacturing is generally complex, time-consuming and does not necessarily result in a catheter that accurately translates the longitudinal motion of the pull wire into uniform on-plane tip deflection.